Study: Y chromosome not going 'extinct'

CAMBRIDGE, Mass., Feb. 22 (UPI) -- A study has contradicted the notion the male sex-determining Y chromosome is steadily shedding genes and is doomed to degenerate, U.S. researchers say.

In a 2002 article in Nature, two Australian researchers examined the rate at which the Y has withered and estimated it "will self-destruct in around 10 million years."

However, Jennifer Hughes, a geneticist at the Whitehead Institute for Biomedical Research in Cambridge, Massachusetts and her colleague David Page say the version of the Y chromosome carried by every human male has lost just a single gene in the 25 million years since humans, chimpanzees and rhesus macaques shared a common ancestor.

They presented their finding in an article published online in Nature Wednesday.

To study its history, Hughes and her team decoded the Y chromosome of the rhesus macaque, which shares a common ancestor with humans and chimps that lived about 25 million years ago.

Macaques are promiscuous, and Hughes said she expected to see that the macaque Y had dropped some genes and duplicated others involved in making sperm.

"It couldn't have been more different," she said. The macaque Y contained just one gene that humans have lost, and human Y has grown much longer than the macaque's but the genes were mostly the same.

"Those are the genes that give me confidence that in another 50 million years, the Y chromosome will still be there," Scott Hawley, a geneticist at the Stowers Institute for Medical Research in Kansas City, Mo., said. "They're not going away."

He suggested the genes have stuck around because, without them, men would be infertile.

"I'm more worried about global warming than the Y chromosome disappearing," Hawley said. "I'm hoping that this paper has settled this controversy."